'Casablanca' sequel storyline unearthed

Cass Warner, the granddaughter of Warner Bros co-found Harry Warner, has unearthed a sequel treatment written by one of the three original Casablanca screenwriters Howard Koch.

According to the New York Post, Warner is hoping to produce a sequel with studio Warner Bros.

Titled Return to Casablanca, Koch's script treatment sees Ilsa and Victor Laszlo (originally played by Ingrid Bergman and Paul Henreid) searching for Rick Blaine after he joins Free French troops opposing the Nazis in North Africa.

Ilsa's son, whose father is Rick, is in his twenties and takes center stage in the proposed movie.

"For whatever reason [Warner Bros] couldn't justify taking interest in it until it was packaged more," Warner told EW. "They didn't go, 'What a ridiculous idea'; they went, 'Bring us [a director] we like and maybe'."

Released in 1942, the original Casablanca starred Humphrey Bogart and Ingrid Bergman, and won Oscars for 'Best Picture', 'Best Director' and 'Best Screenplay'.

AFI named it the third greatest American movie of all time in the 2007 edition of its 100 Years... 100 Movies program.

Warner Bros previously tried to make a Casablanca sequel - titled Brazzaville - after the success of the original, but the project never progressed beyond its script treatment by Frederick Stephani.